President-elect Joe Biden on Tuesday outlined his top three COVID-19 priorities for his first 100 days in office: a 100-day mask-wearing program, 100 million doses of the vaccine into Americans arms in the first 100 days, and getting schools reopened permanently.

"We didn’t get into this mess quickly. We're not going to get out of it quickly," Biden said. "But I'm absolutely convinced that, in 100 days, we can change the course of the disease and change life in America for the better."

Biden warned that distributing the vaccine would be one of the hardest and costliest challenges the country will face and will require the cooperation of Congress.

“We’re gonna need Congress to fully fund vaccine distribution to all corners of the country, to everyone," Biden said. "I'm encouraged by the bipartisan efforts in Congress around a $900 billion economic relief package which I've said is critical, but this package is only a start for more action early next year."

"We'll also need the Trump administration to act now," Biden added, "to purchase the doses it has negotiated with Pfizer and Moderna, and to work swiftly to scale manufacturing to U.S. populations and the world."

ABC News' Molly Nagle contributed to this report.

Washington Gov. Jay Inslee said the state's restriction on social gatherings, restaurants, bars, gyms and religious services will be extended to Jan. 4, 2021.

"We need to buckle down through the holidays," Inslee tweeted.

"The hospitalization projections are scary. We’re already at 80% ICU capacity," Inslee said, adding, "our hospitals are still on the brink."

Washington state has over 184,000 diagnosed COVID-19 cases and at least 2,941 fatalities.

Thirty-five juveniles and 116 adults were arrested at a "super spreader" underground party this weekend in Palmdale, California, said Los Angeles County Sheriff Alex Villanueva.

The sheriff said the party was in clear violation of the governor's stay-at-home order, adding that the party would have been targeted without the pandemic due to allegations of drugs, weapons, prostitution and underage trafficking.

ABC News' Alex Stone contributed to this report.

Massachusetts will roll back its reopening plans on Sunday as cases and hospitalizations rise in the aftermath of Thanksgiving, Gov. Charlie Baker said.

Capacity will be reduced from 50% to 40% in facilities including offices, gyms, places of worship and retail stores, Baker said.

In offices, people must wear masks when they're not alone, and at gyms, customers must wear masks at all times.

Changes are also coming to Massachusetts restaurants. Customers must wear masks at all times except when eating and drinking, and their time at tables will be capped at 90 minutes.

U.S. President-elect Joe Biden on Monday announced key nominations and appointments of his health team, a slate of experts and public officials who will lead his administration's response to the coronavirus pandemic.

"This trusted and accomplished team of leaders will bring the highest level of integrity, scientific rigor and crisis-management experience to one of the toughest challenges America has ever faced -- getting the pandemic under control so that the American people can get back to work, back to their lives and back to their loved ones," Biden said in a statement. "This team of world-class medical experts and public servants will be ready on day one to mobilize every resource of the federal government to expand testing and masking, oversee the safe, equitable and free distribution of treatments and vaccines, reopen schools and businesses safely, lower prescription drug and other health costs and expand affordable health care to all Americans, and rally the country and restore the belief that there is nothing beyond America's capacity if we do it together."

California Attorney General Xavier Beccera is nominated to serve as the Secretary of Health and Human Services.

Dr. Vivek Muthy, a physician and research scientist, is nominated to be the Surgeon General, a role he served during the Obama administration.

Dr. Rochelle Walensky, an expert on virus testing, prevention and treatment, is nominated to serve as director of the Centers for Disease Control and Prevention.

Dr. Marcella Nunez-Smith, an expert on health care disparities, will serve as the COVID-19 Equity Task Force Chair.

As Biden said last week, Dr. Anthony Fauci will stay on in his current role as director of the National Institute of Allergy and Infectious Diseases. Fauci will also serve as Biden's chief medical adviser on COVID-19.

Jeff Zients, co-chair of Biden's transition team who led the Obama administration's National Economic Council, will serve as coordinator of the COVID-19 Response as well as counselor to the president.

Natalie Quillian, a national security expert, will serve as deputy coordinator of the COVID-19 response.

ABC News' John Verhovek contributed to this report.